The aim of the experiments to be carried out is to gain insight into the physiological significance of 2-hydroxylation of estrogen in brain and the role of the 2-hydroxylated or catechol-estrogens in the regulation of reproduction by the central nervous system (CNS). Within this context, we will establish the regional distribution of estrogen 2-hydroxylase in brain, determine if the enzyme is present in neurons, in glia or both, and if it is concentrated at the synaptic terminals. Synaptosomal preparations and adrenergic-neuroblastoma cell line, N1E-115 will be used as simplified in vitro model systems to evaluate the consequences of the ability of catechol-estrogens to inhibit the activity of catechol-o-methyltransferase (COMT) and of tyrosine hydroxylase on the level of activity of these as well as of other determinants of the turnover of catecholamines in neurons. We will examine the ability of a COMT inhibitor to duplicate the effects of catechol-estrogens, in vivo on gonadotrophin and prolactin release in castrated female rats and on the course of CNS differentiation in the newborn female rat. The findings should further our understanding of the mechanisms by which estrogens act to regulate anterior pituitary function and reproductive behavior during the ovulatory cycle and mechanisms by which adrenergic function is modified during pregnancy.